Blastocystis sp. is a commonly reported enteric protistan parasite in faecal specimens with a worldwide
distribution afflicting both humans and a wide range of animals. The aim of this study is to characterize the subtypes
(STs) of Blastocystis sp. isolates from asymptomatic individuals in an urban community in Pateros, Metro Manila,
Philippines. The 600-bp small subunit ribosomal RNA (SSU rRNA) barcoding region of Blastocystis sp. isolates was
amplified and sequenced using the primers RD5 and BhRDr. Subtypes were identified by uploading the sequences onto
the Basic Local Alignment and Search Tool (BLAST) websites, the Blastocystis Subtype (18S) and Sequence Typing
(MLST) Database and by construction of a phylogenetic tree. Twenty-nine (29) out of 35 individuals were detected
positive for Blastocystis sp. ST3 is the most common among the three STs detected (65.5%), followed by ST1 (31.0%)
and ST4 (3.44%). This study showed that DNA barcoding can serve as a helpful tool to investigate the diversity of
Blastocystis sp. in the Philippines